The present invention relates generally to an electroplating apparatus for plating of semiconductor components, and more particularly to an electroplating apparatus, including a segmented anode array comprising a plurality of concentrically arranged anode segments which can be independently operated to facilitate uniform deposition of electroplated metal on an associated workpiece.
Production of semiconductive integrated circuits and other semiconductive devices from semiconductor wafers typically requires formation of multiple metal layers on the wafer to electrically interconnect the various devices of the integrated circuit. Electroplated metals typically include copper, nickel, gold and lead. Electroplating is effected by initial formation of a so-called seed layer on the wafer in the form of a very thin layer of metal, whereby the surface of the wafer is rendered electrically conductive. This electroconductivity permits subsequent formation of a so-called blanket layer of the desired metal by electroplating in a reactor vessel. Subsequent processing, such as chemical, mechanical planarization, removes unwanted portions of the metal blanket layer formed during electroplating, resulting in the desired patterned metal layer in a semiconductor integrated circuit or micro-mechanism being formed. Formation of a patterned metal layer can also be effected by electroplating.
Subsequent to electroplating, the typical semiconductor wafer or other workpiece is subdivided into a number of individual semiconductor components. In order to achieve the desired formation of circuitry within each component, while achieving the desired uniformity of plating from one component to the next, it is desirable to form each metal layer to a thickness which is as uniform as possible across the surface of the workpiece. However, because each workpiece is typically joined at the peripheral portion thereof in the circuit of the electroplating apparatus (with the workpiece typically functioning as the cathode), variations in current density across the surface of the workpiece are inevitable. In the past, efforts to promote uniformity of metal deposition have included flow-controlling devices, such as diffusers and the like, positioned within the electroplating reactor vessel in order to direct and control the flow of electroplating solution against the workpiece.
In a typical electroplating apparatus, an anode of the apparatus (either consumable or non-consumable) is immersed in the electroplating solution within the reactor vessel of the apparatus for creating the desired electrical potential at the surface of the workpiece for effecting metal deposition. Previously employed anodes have typically been generally disk-like in configuration, with electroplating solution directed about the periphery of the anode, and through a perforate diffuser plate positioned generally above, and in spaced relationship to, the anode. The electroplating solution flows through the diffuser plate, and against the associated workpiece held in position above the diffuser. Uniformity of metal deposition is promoted by rotatably driving the workpiece as metal is deposited on its surface.
The present invention is directed to an electroplating apparatus having a segmented anode array, including a plurality of anode segments which can be independently operated at different electrical potentials to promote uniformity of deposition of electroplated metal on a associated workpiece.